1. Field of the Invention
The present invention relates to a fabric presser foot device of a sewing machine and, more particularly, to a fabric presser foot device of a sewing machine used when a fabric having a relatively large thickness and poor surface smoothness, such as a fabric for wet suit of which surface is covered or coated with a waterproof rubber membrane, is sewed in the state that its end portions are adjoined or overlapped with each other.
2. Description of the Background Art
Such a type of fabric presser foot device has generally been constructed as follows. For the purpose that a fabric set on a throat plate is linearly and smoothly fed without causing any lateral deviation in the sewing direction, a fabric presser foot such as a plate spring of a length extending from the upstream position to the downstream position than a needle location in the sewing direction is disposed at a lower end portion of a presser bar allowing for the vertically reciprocal motion of this long fabric presser foot, in order to resiliently press the fabric portions at their locations corresponding to a pair of front and rear feed dogs disposed below the throat plate, to the upper surface of the throat plate, that is, the front and rear feed dogs.
In this conventional fabric presser foot device of a sewing machine comprising the fabric presser foot such as a plate spring having a long pressing surface along the sewing direction, when sewing a fabric having a high surface smoothness, e.g., a knit, because of the high smoothness between the pressing surface of the fabric presser foot and the surface of the fabric (i.e., a small frictional resistance), no problem occurs in the fabric feed. On the other hand, when sewing a fabric having poor surface smoothness, such as a fabric for wet suit of which surface is covered or coated with a waterproof rubber membrane, due to the poor smoothness between the pressing surface of the fabric presser foot and the surface of the fabric (i.e., a large frictional resistance), the brake is applied therebetween, thus making it impossible to feed the fabric. Even if possible, in this state it is liable to cause the disadvantages that the non-uniform and unstable feed may damage the fabric and deteriorate the finish.
To avoid the disadvantages in sewing a fabric having poor surface smoothness, e.g., the mentioned fabric for wet suit, there has conventionally been taken a means of applying oil, such as a lubricating oil, to the surface of the fabric before sewing, for the purpose of increasing the surface smoothness. This means, however, involves the oil application to the fabric and oil removing after sewing, which are not directly related to the sewing operation. Therefore, it is unavoidable that not only the efficiency of the overall sewing operation is lowered but also the sewing product is stained by the oil.
Accordingly, it is an object of the present invention to provide a fabric presser foot device of a sewing machine with which no lateral drift of a fabric is caused and, even in sewing a fabric having poor surface smoothness, the fabric can be fed reliably, smoothly and uniformly without requiring such an operation of applying oil to the fabric.
The above mentioned object is attained according to the present invention by a fabric presser foot device of a sewing machine for the type having a throat plate and a pair of front and rear feed dogs disposed below the throat plate to forcedly convey a fabric set on the throat plate in the sewing direction, wherein the improvement comprises: a presser foot body fixedly supported to a lower end portion of a presser bar supported to a sewing arm part so that it is movable vertically reciprocally, the presser foot body having a needle location through which a needle moves vertically; a fabric presser foot disposed on the downstream side than the needle location in the sewing direction to resiliently press the fabric to the upper surface side of the throat plate, the fabric presser foot being attached to the presser foot body; and a rolling body for feeding and guiding the fabric disposed on the upstream side than the needle location in the sewing direction, the rolling body being brought into contact with the upper surface of the fabric and being rotatably supported so that its contact portion is successively changed along with the fabric feed.
With this construction, the fabric set on the throat plate can be pressed to the upper surface of the throat plate by the fabric presser foot disposed on the downward side than the needle location in the sewing direction and the rolling body disposed on the upstream side than the needle location in the sewing direction, and the fabric is fed and guided linearly in the absence of any lateral drift by the forced feed force of the front and rear feed dogs. Further, since the rolling body of which contact portion with the upper surface of the fabric is successively changed with the fabric feed is employed as a pressing means on the upstream side in the sewing direction, even when sewing a fabric of extremely poor surface smoothness, such as a fabric for wet suit of which surface is covered or coated with a waterproof rubber membrane, the fabric can be fed and guided reliably, smoothly and in a stable uniform manner by minimizing the frictional resistance between the rolling body and the fabric surface, without requiring any oil application to the fabric surface before sewing and any oil removing after sewing. It is therefore avoidable that the fabric is damaged and the sewing finish is deteriorated.
A rolling body of the fabric presser foot device of the invention may be disposed at a sewing arm part, separately from the presser foot body to which the fabric presser foot is attached, so as to be movable vertically reciprocally. Alternatively, a rolling body may be supported to a support block coupled to the presser foot body, so that it can move vertically reciprocally in synchronism with the vertical reciprocal motion of the presser foot body. This construction can simplify the overall structure of the presser foot device and also reliably synchronize the timing of the vertical motions of the fabric presser foot and the rolling body.
As a rolling body of the fabric presser foot device, a roller or rotary belt may be used, and a roller is preferable in terms of structure.
Alternatively, the support block may be attached to the presser foot body so that it can vertically slide and be fixed thereto. By the vertical slide of the support block, the height of the rolling body is adjustable according to the thickness of the fabric. With this construction, according to the thickness of the fabric to be sewed, the height of the rolling body is adjusted to optimize the fabric pressing force. This enables to feed and guide the fabric reliably, smoothly and uniformly, irrespective of the thickness of the fabric.
Alternatively, the rolling body may be divided into two in the axis of rotation and a gap capable of absorbing a difference between the overlapped end portions of a fabric is formed between the opposed end surfaces of the divided rolling body. With this construction, when sewing a thick fabric having poor surface smoothness with its end portions overlapped with each other, a difference between the overlapped ends at which the thickness is locally increased than other portions can be absorbed by the gap. Even when such a thick fabric of poor surface smoothness is sewed with its end portions are overlapped with each other, a reliably smoothly uniform feed performance can be exhibited without excessively increasing the pressing force of the rolling body.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.